‘Spin-only’ magnetic moment is the same for which of the following ions?A. ${\text{Ti}}^{3+}$ B. ${\text{Cr}}^{2+}$ C. ${\text{Mn}}^{2+}$ D. ${\text{Fe}}^{2+}$ E. ${\text{Sc}}^{3+}$

The spin-only magnetic moment depends on the number of unpaired electrons ($n$).A. ${\text{Ti}}^{3+}$ ($Z=22$): $[\text{Ar}]3d^1$. $n=1$.B. ${\text{Cr}}^{2+}$ ($Z=24$): $[\text{Ar}]3d^4$. $n=4$.C. ${\text{Mn}}^{2+}$ ($Z=25$): $[\text{Ar}]3d^5$. $n=5$.D. ${\text{Fe}}^{2+}$ ($Z=26$): $[\text{Ar}]3d^6$. $n=4$ (one pair).E. ${\text{Sc}}^{3+}$ ($Z=21$): $[\text{Ar}]3d^0$. $n=0$.Iions B and D both have $n=4$ unpaired electrons, so they will have the same spin-only magnetic moment ($\mu =\sqrt{n(n+2)}=\sqrt{24}\approx 4.9\text{BM}$).